bjerkan



March 3, 1964 T. J. BJERKAN GRAIN DRYER 2 Sheets-Sheet 1 Filed June 26, 1962 INVENTOR. 72600'0/6 J fiy'ar/w A ffarne y.

United States Patent 3,123,234 GRAIN DRYER Theodore J. Bjerkan, 7304 Cherokee Drive, Prairie Village, Kans. Filed June 26, 1962, Ser. No. 205,3% 3 Claims. (Cl. 214-17) This invention relates to new and useful improvements in grain dryers, and has particular reference to grain dryers wherein grain deposited in a bin having a perforated bottom is dried by hot air forced upwardly through said perforated bottom and through the bed of grain resting thereon. Still more specifically, this invention relates to a device for levelling the grain in the bin so that the bed of grain will be of uniform depth over the entire area of the bin.

In grain dryers of the character described, grain is usually deposited therein from the top of the bin through a restricted opening, and tends to become piled more deeply directly beneath the inlet opening than elsewhere, coming to rest in a conical pile the angle of which is the normal angle of repose for the grain. Regardless, however, of the reason which causes the grain bed to assume a nonuniform depth over the area of the bin, such non-uniform depth causes a serious malfunction in the drying operation, in that the hot air passes more easily through the thinner portions of the grain bed than through the thicker portions, with the result that a disproportionately great share of the air passes said thinner portions. Therefore, the grain in the thinner portions of the grain bed is dried much more rapidly than the grain in the thicker portions,

and may actually be seriously damaged .by overheating and partial cooking, before the grain in the thicker portions of the grain bed have been dried to the extent desired. Only by spreading the grain evenly so that the bed has a uniform thickness throughout its horizontal area can uniform flow of hot air throughout the mass of grain, and hence uniform drying of the grain, be obtained. The provision of novel apparatus for performing this levelling operation is the primary object of the present invention.

Another object is the provision of a levelling apparatus of the character described which also is adaptable for use in insuring complete and thorough emptying of grain from the bin after the drying operation is completed, by moving the grain to an outlet opening in the bottom of the bin, through which the grain passes by gravity.

Other objects are simplicity and economy of construction, efficiency and dependability of operation, and adaptability for use in bins loaded to any depth.

With these objects in view, as well as other objects which will appear in the course .of the specification, reference will be had to the drawing, wherein:

FIG. 1 is a vertical sectional view through a grain dryer embodying the present invention, shown partially loaded with grain,

FIG. 2 is a sectional view taken on line IL-II of FIG. 1, with the grain omitted.

FIG. 3 is an enlarged, fragmentary sectional view taken on line III-Ill of FIG. 1, and

FIG. 4 is an enlarged, fragmentary sectional View taken on line IV-IV of FIG. 2.

Like reference numerals apply to similar parts throughout the several views, and the numeral 2 applies generally to a bin formed customarily of sheet metal, and being cylindrical with its axis disposed vertically. It is provided with a bottom wall 4 and with a top cover 5 which is of inverted conical shape and is provided with a central inlet opening 6 through which grain 8 to be dried may be fed into the bin from any suitable source through a filling spout 10. Said cover is attached to and spaced slightly above the bin by a plurality of brackets 12, whereby to form a peripheral opening 14 for the egressof warm air, as will presently appear.

Bin 2 is provided with a horizontal false bottom 16 spaced above bottom 4, whereby to form a plenum chamber 17 therebetween, into which hot air under pressure is forced through an air tube 18, the air being heated and impelled by any suitable means, not shown, external to the .bin. False bottom 16 is perforated over substantially its entire area as indicated at 20, whereby air from plenum chamber 17 travels upwardly through the grain in the bin to dry it, and escapes from the bin through openings-6 and 14. False bottom 16 is provided with a central grain outlet opening 22, which opens into a well 24 formed by a cylindrical wall 26 extending between bottom 4 and false bottom 16. Grain may be evacuated from well 24 by a horizontal auger 28 disposed rotatably in an auger tube 39 extending from well '24 to a point exterior to the bin. The anger is rotatably driven by any suitable source of power, not shown.

The spreading device forming the specific subject matter of the present invention includes a vertical shaft 32 disposed coaxially with the bin and extending substantially the full height of said bin, said shaft being rotatably journalled at its lower end in a bearing 34 supported in well 24 by a spider 36 afiixed to cylindrical wall 26. At its upper end, said shaft is operably connected through a geared, right-angled speed reducer 38 to an electric motor 40 which is afiixed to the inner surface of cover 5 by suitable brackets 42. For reasons which will presently appear, said motor is reversible so as to rotate shaft 32 selectively in either direction. Said shaft is provided with a radially projecting key 44 extending substantially the full length thereof.

A hub member 46 constituting a generally rectilinear block is mounted for vertical sliding movement on shaft 32. Said hub is provided with a keyway 48 (see FIG. 3), in which key 44 engages to prevent rotation of said hub on the shaft. Rigidly affixed at their inner ends to hub 46, each by a pair of screws 5%, are a pair of arms 52. Said arms extend horizontally in opposite directions from the hub, each to a point closely adjacent the wall of bin 2, and are curved spirally in a horizontal plane, as best shown in FIG. 2. When shaft 32 is turned in the direction of arrow '52 in FIG. 2, the convex faces of said arms constitute the leading edges, while when shaft 32 is turned in the direction of arrow 54, the concave faces of said arms are the leading edges. Both of these faces of the arms are vertical and are disposed at right angles to the direction of travel of said arms as they rotate.

A thin sheet metal pan 56 is afiixed to the convex face of each arm 52, at the outer end thereof, and extends from said arm in a direction to precede said arm when the arms are rotating in the direction of arrow 52. Said pans are generally horizontal and coplanar with the lower edges of the arms. Each pan is provided along one edge with an upturned flange 58 which is secured to the associated arm by means of screws 60, while the leading edge of each pan, when the arms rotate in the direction of arrow amazes 52, is curved upwardly to form a lip 62 which is inclined upwardly from the body portion of the pan.

In operation, as grain is deposited in bin 2 through spout 10, the grain 8 has a tendency to pile most deeply in the central portion of the bin, and less deeply in the peripheral portions of the bin. That is, it Will tend to fall in a conical pile the angle of which is the angle of repose of the grain. Under these circumstances, hot air traveling upwardly through the grain bed from plenum chamber 17 will tend to concentrate in the peripheral portion of the bed where the resistance to air flow is smallest, While much less air will flow through the central portion of the grain bed where resistance to air flow is greater. This results, as previously described, in uneven, inefiicient drying of the grain, and in possible damage to portions of the grain due to overheating, such as partial cooking and destruction of the germinating power.

The present invention overcomes these difiiculties by spreading the grain to an even depth over the entire area of the bin. Motor 4t? is set in operation to turn shaft 32 in the direction of arrow 52 as the bin is being filled. The convex faces of arms 52, which are then the leading faces of the arms, impel grain from the center of the bin outwardly toward the periphery of bin to even the depth of the grain bed, due to their spiral curvature, while pans 56 ride or float on the surface of the grain, and are of sufficient area to prevent the arms from sinking or digging into the grain to any appreciable extent. If grain should cover the pans, as could occur if grain were deposited in the bin before motor 40 were started, the upturned lips 52 of the pans will cause the pans to be moved upwardly through the grain until the arms again are riding the surface of the grain, the vertical movement of the arms being made possible by the sliding movement of hub 46 on shaft 32. 'It would, in fact, be quite possible to fill the bin completely with grain, with arms 52 resting on floor 16, before starting motor 4th. The pans 56 would still plane their way upwardly through the grain bed, and the grain surface would be levelled. However, due to the excessive power requirements of starting and maintaining rotation of the arms while under a heavy bed of grain, it is preferable to rotate the arms during the entire filling operation. Also, it has been found that straight, radially disposed arms may be used in place of the spirally curved alrms shown. Straight radial arms will level the grain, but much more slowly and ineffioiently in that a greater number of revolutions of the arms are then required. It is also possible to dispense with pans 56 by using arms 52 of a very light weight so that they will have sufiicient buoyancy to ride the surface of the grain rather than digging However, such light weight arms inherently take a smaller bight into the grain and move less grain per revolution of the arms, and are hence slower and less efiicient in operation. Also, pans 56 could be replaced by flanges formed integrally with the arms. It will be apparent also that arms 52 could still perform the function of urging grain outwardly toward the periphery of the bin even if they were not spirally curved as shown. They could be straight, for example, if they were inclined rearwardly from their direction of travel, toward their outer ends. However, the spiral form provides that a tangent to the convex face of each arm, at any point in its length, will be inclined at the same angle to a radius drawn to that point of the arm from shaft 32. This uniform angle of attack provides a smoother, more efiicient spreading action, and is therefore preferable. a

When emptying grain from the bin after completiombf the drying operation, auger 28 is of course set in action to withdraw grain from well 24. Were it not for arms 52, however, the bin could not be emptied completely, since while the grain directly over outlet opening 22 would flow out, the remaining grain would come to rest with an inverted conical surface sloping upwardly and outwardly from the edge of opening 22 toward the outer edge of the bin, at the angle of repose of the grain. To prevent this, motor 40 is reversed as the bin is emptied, to cause rotation of shaft 32 in the direction of arrow 54. The concave faces of arms 52 are then the leading edges, and due to their inwardly facing concave curvature they impel grain inwardly from the peripheral portion of the bin toward its center, where it of course falls through outlet opening 22 into well 2 In this manner, the bin may be thoroughly emptied. This dual function of the arms 52 is an important feature of my invention.

While the structure as described is specifically adapted to bins having central inlet and outlet openings as shown, the levelling and emptying functions of arms 52 are readily adaptable to bins having inlet and outlet openings disposed other than centrally, for example in bins having inlet and outlet openings at or near the periphery of the bin. In that case, during the filling operation, the arms could be caused to rotate in the direction of arrow 54-, so that the curvature of the arms would urge grain toward the center of the bin, it being further understood that pans 56 would be shifted to extend from the convex faces of the arms. Also, when emptying the bin, the arms would be caused to rotate in the direction of arrow 52, so that their curvature would urge grain toward the peripherally disposed outlet opening.

While I have shown and described a specific embodiment of my invention, it will be readily apparent that all of the variations thereof described above, as well as other minor changes of structure and operation, could be made without departing from the spirit of the invention as defined by the scope of the appended claims.

What it claim as new and desire to protect by Letters Patent is:

1. In a grain drying machine comprising a bin having a top grain inlet opening of restricted area and including means for forcing air upwardly through grain deposited therein, a grain levelling device comprising:

(a) a vertical shaft mounted coaxially and rotatably within said bin,

(11) means for rotating said shaft in one direction,

(0) a hub carried on said shaft for free axial sliding movement but secured against relative rotation thereon,

(d) one or more arms affixed to said hub and extending horizontally therefrom to points adjacent the periphery of said bin, and

(e) a planar horizontal pan member affixed to each of said arms in generally coplanar relation with the lower edge thereof and extending therefrom in the direction of rotation thereof, the leading edge of said pan member being formed to present an upwardly inclined lip, where-by as said shaft is rotated said pan members will seek and be supported on the surface of the grain contained in said bin.

2. In a grain drying machine comprising a bin having a top grain inlet opening and a bottom grain outlet opening, both of said openings being of restricted area and disposed substantially axially of said bin, and including means for forcing air upwardly through grain deposited therein, a grain levelling device comprising:

(a) a vertical shaft mounted coaxially and rotatably Within said bin,

(12) reversible means for rotating said shaft selectively in either direction,

(0) a hub carried on said shaft for free axial sliding movement but secured against relative rotation thereon, and

(d) one or more arms affixed to said hub and extending horizontally therefrom to points adjacent the periphery of said bin, each of said arms being inclined in like manner in a horizontal plane from a line radial to said shaft, whereby when said shaft is rotated in one direction said arms will urge grain toward the periphery of said bin, but will urge grain toward the center of the bin when said shaft is rotated in the opposite direction.

5 6 3. The structure as defined in claim 2 with the addi- References Cited in the file of this patent tion of:

(a) a planar horizontal pan member affixed to each UNITED STATES PATENTS of said arms in generally coplanar relation with the 750,241 k 9, 1 0 lower edge of said arm, each of Said pan me e 5 2,605,692 Kranick Aug. 5, 1952 being provided with an upwardly inclined lip along 3,001,465 13 1 Sept. 26, 196 1 the edge thereof which is the leading edge when san FOREIGN PATENTS arms are being rotated in a direction to urge grain toward the periphery of the bin. 29 .339 Switzerland Dec. 1, 195 3 

1. IN A GRAIN DRYING MACHINE COMPRISING A BIN HAVING A TOP GRAIN INLET OPENING OF RESTRICTED AREA AND INCLUDING MEANS FOR FORCING AIR UPWARDLY THROUGH GRAIN DEPOSITED THEREIN, A GRAIN LEVELLING DEVICE COMPRISING: (A) A VERTICAL SHAFT MOUNTED COAXIALLY AND ROTATABLY WITHIN SAID BIN, (B) MEANS FOR ROTATING SAID SHAFT IN ONE DIRECTION, (C) A HUB CARRIED ON SAID SHAFT FOR FREE AXIAL SLIDING MOVEMENT BUT SECURED AGAINST RELATIVE ROTATION THEREON, (D) ONE OR MORE ARMS AFFIXED TO SAID HUB AND EXTENDING HORIZONTALLY THEREFROM TO POINTS ADJACENT THE PERIPHERY OF SAID BIN, AND (E) A PLANAR HORIZONTAL PAN MEMBER AFFIXED TO EACH OF SAID ARMS IN GENERALLY COPLANAR RELATION WITH THE LOWER EDGE THEREOF AND EXTENDING THEREFROM IN THE DIRECTION OF ROTATION THEREOF, THE LEADING EDGE OF SAID PAN MEMBER BEING FORMED TO PRESENT AN UPWARDLY 